This project examines the physiological effects and the underlying biochemical mechanisms of the action of the delta opioid peptides and a related protein factor HIT (Hibernation Induction Trigger) in organ preservation and protection. In a lung transplantation experiment, the lung, after 24 hours of preservation with the HIT, functioned normally when transplanted into the host animal. In another experiment, the delta opioid peptide DADLE was examined for potential myocardial protective action using isolated rabbit hearts. Before subjecting the heart to ischemia, the hearts received a single perfusion of DADLE over a period of 15 minutes. This procedure of DADLE preperfusion dramatically improved recovery of myocardial functions following 18 hours of global ischemia at 4EC when compared to controls. We are currently examining the potential use of DADLE in certain types of CNS damage.